Finally component designers are seeing sense and designing comfort into components without sacrificing performance. Syntace's reworked P6 seatpost has a new Hi-Flex construction.
Syntace have been making their fantastic P6 seatpost in carbon and plain old 7075 alloy, but recently they've redesigned their well -regarded classic with a one piece carbon shaft and head (the previous carbon version uses a carbon shaft bonded to an alloy head) and call it the P6 Hi Flex. By incorporating the head and shaft together in one piece, Syntace can save weight (carbon is lighter than alloy)and create a seatpost which is able to extend its working length to offer, according to Syntace double the vibration damping of the old P6. Well talk is cheap and manufacturer's claims often not worth the paper it's written on, so is this going to work in real life?
Anyone who bags a lot of miles will tell you that often it's not any lack of fitness that forces you to turn for home on long rides, but the accumulation of road vibrations into your lower back. It's a slow insidious burn, small vibrations built up mile on mile, which work up from your wheels moving straight through the seat stays and into your traditionally uniformly stiff seatpost and upwards into the saddle where a couple of millimetres of foam padding is your only relief. You can wear good shorts, and keep your butt in and out of the saddle. You can't avoid it, but you can reduce the negative effect with the Hi Flex.
OK, there are several ways you can benefit, firstly there's the post ability to help you with actual impacts. Stuff like those 'hidden' pot holes which normally unseat you and jar your back. With the Hi Flex you'll still wince, but only for the pain caused to your tyre and wheel rim. You might still get bumped off the saddle, but not as much as with a regular post. If this sounds like a very low level win, stay with this... there's a bigger win. It's the smaller less obvious vibrations, the ones which we feel through the chamois, the ones which build hour up on hour and eventually germinate into back ache and numb bum which the Hi Flex really helps with.
The clever stuff is partly in the lay-up; the type and directional orientation of the carbon fibres and partly in the internal shaping of the shaft. Syntace ovalise the internal shape with the oval shape running perpendicular to the frame, this invites a tendency to flex, but crucially only in the rearwards direction. Before you worry it's millimetres we're dealing with, not some sloppy feeling fairground ride or one that can in any way be described as suspension. Under maximum load the Hi Flex post will deflect around 20mm, though mostly it's going to be between 3 and 10mm. Initially you'll feel the saddle tilting very slightly, though because the movement is small and happening very rapidly all the time it very quickly feels completely normal.
The Hi Flex offers a subtle change in ride sensation – one of extra smoothness. Our 400mm 27.2mm diameter 226g test sample gave a feel like a slightly bigger, softer rear tyre – only without the associated squirmy handling. Think about it in terms of running a 25 or 28c tyre with 20psi less pressure in place of your regular 23c 120psi rubber. Added comfort without reducing the net performance. It's a palpable net effect. You'll sense it within a few miles and definitely feel the benefit at the tail end of a long multi hour ride.
Once you realise that using a seatpost like the HiFlex can allow you to remain seated and focused on the smooth consistent turning of the pedals, rather than trying to ease off the saddle to relieve the dull ache behind your jersey pockets, you'll be sold. It's the same reasoning behind using flexible engine mounts in cars. Except you are the big heavy engine, you need to be able to be better isolated from the chassis. The P6 Hi Flex allows exactly that.
Other features of the Hi Flex are as per the existing P6 and are worth a recap as they're some of the finer design elements of any seatposts. The saddle clamp uses extra long 52mm lower rail guides and super short 32mm upper rail guides made from cold forged alloy. This configuration gives maximum support for saddle rails while also providing unmatched fore/aft saddle positioning options. The saddle clamps can be adjusted with a 30 degree range, beating most other posts with ease. Add in properly offset heads to the twin adjuster bolts which means you can make fine adjustments without the tool hitting the shaft, and you can see why P6 owners covet their seat posts.
Available in 27.2, 30.9, 31.6mm diameters and in 300, 400 or 480mm lengths, Syntace offer the P6 Hi Flex with a satisfyingly long 10 year guarantee, something they can do with confidence thanks to extensive in house testing which uses leading edge test equipment (Syntace's testing is recognised as being some of the most rigorous in the cycling industry). We've never seen a broken one, or even a bent one for that matter. The result is a seatpost that simply makes riding more pleasurable and we think improves ride performance – hey that can't be bad.
Effectively damps road vibration, looks awesome and still offers unbeatable levels of adjustment.
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road.cc test report
Make and model: Syntace P6 Flex post
Size tested: 27.2mm x 400mm
Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?
Syntace say, "The P6 Hi Flex offers twice the amount of shock absorbtion to the previous model out loss of riding control"
Tell us how the product performed overall when used for its designed purpose
Syntace are clear about the ability/effect of the P6 Hi Flex and after extensive testing we think they're honest, accurate statements.
Tell us what you particularly liked about the product
Apart from actually doing what it claims, damping vibration the P6 Hi Flex is both good looking and lightweight
Tell us what you particularly disliked about the product
There's nothing to complain about here. A good idea well executed.
Did you enjoy using the product? Yes.
Would you consider buying the product? Yeah, I would.
Would you recommend the product to a friend? Yes.
About the tester
Age: 41 Height: 5'9 Weight:
I usually ride: My seven titanium My best bike is:
I've been riding for: Over 20 years I ride: Every day I would class myself as: Expert
I regularly do the following types of riding: cyclo cross, club rides, sportives, mtb, A bit of everything